Mound ants

Mound ants, Formica sp., build large conspicuous nests in open fields and in open areas in woodlots and forests. Their large mounds are constructed of soil brought up from excavated galleries below the nest. Large colonies may include over 250,000 workers and over a 1,000 egg laying queens. The mound acts as an incubator for mound ant larvae and pupae. The ants kill nearby vegetation including small trees and shrubs to keep shade off of the mound. They do this by chewing a small hole in the bark and injecting formic acid into the wound. Not surprisingly, they can be a real pest in nurseries and Christmas tree plantations. They will often aggressively defend the mound by biting those who dare to disturbed it. This can make life very unpleasant for those who happen to share their yards with mound ants. Mature mounds may reach over 30 inches in height, six feet across and the subterranean galleries may go to a depth of six feet beneath the ground. The nest’s size and depth make them very difficult to kill off.

 Mound ants feed on most any type of small insect or arthropod that they can find as they forage or hunt over the ground. The ants also collect the honeydew secretions from sap-sucking insects such as aphids and leafhoppers. They rarely enter homes or buildings in search of food, which a very good thing. They are pretty much harmless. They don’t bother people or pets unless the mound is disturbed.

 If you feel you must kill off the ants, then dusting the top of the mound and around the perimeter with an insecticidal dust like Sevin Garden Dust and then raking the top of the mount can be effective if repeated enough times. Raking the mound causes the ants to move to the surface to repair the damage to their galleries. The dust is picked up by the ants and spread throughout the colony. Repeat this process until no more activity is observed. Keep in mind that because of the colony’s large size and the determination of its occupants, mound ants are very difficult to control.

Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.

Carpenter ants, Camponotus sp. (Hymenoptera: Formicidae)

Carpenter ants are one of the largest and most common ants in Michigan. Unlike termites, they only nest in wood and do not eat it. Outdoors, they commonly nest in hollow trees and stumps. Finding them indoors during the summer does not necessarily mean they are nesting in your house, they may just be coming in from outside.  However, the presence of carpenter ants in homes during the winter months, when it is too cold outside for ants to be active, is a very strong indication a colony of carpenter ants exists inside the building.  When they do nest indoors, they prefer an enclosed space that remains wet or damp, more or less, or a permanent basis. Carpenter ants are attracted to excessive moisture conditions around windows, doors, showers, bathtubs, dishwashers, leaky pipes and drains, and under leaky roof shingles or roof vents.  They have also been found in dry areas such as hollow-core doors and false beams, and blueboard foam insulation. 

The presence of winged carpenter inside the home during the summer, does not by itself, mean you have a carpenter ant nest in your home.  Winged ants are the reproductive forms of the colony and usually issue from the colony in late spring.  They drop their wings soon after mating and begin to search for a suitable nesting site.  They commonly enter structures but only rarely do they succeed in finding a nest site and most winged forms die before establishing a nest.

The best method of controlling an indoor colony of carpenter ants is to locate the nest and treat it directly with a persistent insecticide registered for indoor use.  Insecticides labeled for this use include Ortho’s Home Defense Max. Most importantly, be sure to make any repairs, if necessary, to keep the area dry. 

Another approach that is gaining strength in the pest control industry is to spray all possible entry points on the outside of the building (where sills and foundations meet, around doors, windows, vents and utilities) with fipronil (sold as Termidor SC or Taurus SC).  Fipronil forms a non-repellent barrier that the ants cannot detect.  Carpenter ants must leave the house to forage outside for food so they will pick it up when the come and go and spread it through the colony. Neither of these insecticides is widely available but they can be purchased over the internet or at John Deere Landscaping (formerly Lesco’s).  Neither product is labeled for use inside homes and other buildings.  Termidor and Taurus should only be applied during the warmer months of the year when the ants are active outside. Taurus is less expensive. 

Both can be purchased online at:
http://pestcontrol.domyownpestcontrol.com/search?w=taurus%20sc
http://pestcontrol.domyownpestcontrol.com/search?view=grid&w=termidor+sc

Commercially prepared ant baits are available but I don’t know how effective they are controlling carpenter ants; they are probably more effective in the winter when the ant’s favorite foods are not available.  One internet supplier of carpenter ant baits is doyourownpestcontrol.com.  They sell at least three bait products for carpenter ants.  I recommend trying the Maxforce Carpenter Ant Bait Gel first and see how that works before purchasing one of the others.  See their carpenter ant baits at: http://www.doyourownpestcontrol.com/carp.htm

Finding the nest can be difficult since many of the ant’s favorite nesting sites are inaccessible. Begin looking in the rooms where the greatest numbers are found and observe where they go or come from.  Carpenter ants are nocturnal and are most active at night.  Carpenter ants are very tidy housekeepers and quickly remove wood shavings, food debris and dead co-workers from the nest area.  In many cases, this nest debris accumulates in basements beneath the nest area, so look for accumulations of coarse sawdust and dead ants along and on top of basement walls and in cobwebs. 

Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.